1. Field of the Inventions
The present inventions relate to an outboard motor mounted, for example, on a small watercraft or the like.
2. Description of the Related Art
Typically, outboard motors include a power transmission mechanism for transmitting rotational power of the crankshaft of an engine to a propeller through a drive shaft. An advancing/reversing-switching mechanism (also known as a forward-reverse-neutral transmission) connects the drive shaft with a propeller shaft and allows the propeller shaft to be shifted between neutral, forward, and reverse thrust modes.
The connections between various components of the drive trains typically used in outboard motors are provided with small clearances, often referred to as mechanical “play” to reduce friction at these connections and for other reasons. As such, the components forming the connections collide with each other at various times. For example, when the transmission is shifted, and when there are variations in the torque output from the engine, these components strike each other.
The collisions between these parts generate noises. These noises are particularly noticeable in large outboard motors such as those including high horse power four-stroke engines. Further, in outboard motors with high horsepower, the passengers of the associated boat can experience unpleasant shocks due to abrupt change in propulsion force produced, for example, at the time of shifting.
Thus, several different designs have been proposed for absorbing shocks, such as those designs in Japanese Patent Nos. JP-A-Sho 60-215495 (P1–P7, FIG. 1–FIG. 13) and JP-A-2000-280983 (P1–P10, FIG. 1–FIG. 13).
Japanese Patent No. JP-A-Sho 60-215495 discloses an arrangement in which a drive shaft is divided into a driving section and a driven section, and a shock absorbing device is disposed between the two sections. Japanese Patent No. JP-A-2000-280983 discloses an arrangement in which either a drive shaft or a propeller shaft is divided into a driving section and a driven section, and a shock absorbing device is disposed between two sections.